This invention relates to hydraulic control apparatus for automatic remote control of a hydraulic actuating ram, and is particularly, though not exclusively, concerned with remote control of movement of the nozzle of a high-velocity water jet monitor.
In a number of mining industries, for example the clay industry, a high-pressure water jet, from the nozzle of a water jet monitor, is used to wash minerals from the earth. This washing process has been improved in recent years by increasing the velocity of the water jet and by directing the water jet more effectively at the area to be washed, washing being carried out by traversing the jet of water continually back and forth over a selected area of the earth. Because of the high pressure of water involved and the time required to wash a particular area effectively it is desirable to employ remote control of the movement of the nozzle so that the operator can supervise the monitor from a safe distance and avoid repetitive manual control over long periods. One method of traversing the jet back and forth is by adapting the nozzle of the monitor to be movable, for example by pivoting, by means of a hydraulic actuating ram or rams.